Novel N-quinonyl amino acids and their transformation to 3-substituted p-isoxazinones

Summary. Quinonyl amino acids are building blocks in the preparation of peptides which target the quinonic drug to cancer damaged area. Novel N-(3-chloro-1,4-dihydro-1,4-dioxonaphthalen-2-yl)-α-amino acids 1a–f were prepared by direct substitution of 2,3-dichloro-1,4-naphthoquinone. The quinonic moiety was reduced by NaBH₄ to yield the corresponding hydroquinones 2a–f, which in acidic conditions underwent internal cyclization to yield the 3,4-dihydro-2H-naphth[1,2-b]-1,4-oxazine-2-ones (six-membered azlactones) 3a–f. Received February 2, 2000 Accepted March 29, 2000